1. Field of the Invention
The present invention relates to antiskid devices for wheels and, more particularly, to snow-chain type assemblies for vehicle wheels.
2. Discussion of the Related Art
Everyone is aware of the problems encountered by the driver who is forced to equip his vehicle with chains on the berm of a road and often in bad atmospheric conditions. In order to avoid this difficult fitting, automatic systems for positioning antiskid devices have previously been proposed.
French Patent No. 2,492,744, for example, describes an antiskid device for a vehicle wheel comprising a return member designed to automatically position a chain or detachable antiskid rolling track on the periphery of the wheel and to hold it there.
Because of the relative movement of the chain with respect to the peripheral surface of the tire, it is desirable to mount the return member so as to rotate with respect to a central housing for fastening radial linking elements or arms which are indirectly attached to said rolling track. A system of this type is described in European Patent Application No. 87115502.4 of the Applicant, and which corresponds to U.S. Pat. No. 4,922,982, which more particularly relates to a return member and its assembly with respect to the central housing.
In this construction, use is made, moreover of articulation elements disposed between the chain and the arms in order to enable any deformations, which occur in the rolling track as it strikes the ground, to be followed. Such a deformation of the rolling track involves a pivoting with respect to the tangent to the wheel. The necessary articulation creates a point of weakening of the system, which is, of course, undesirable.
In German Patent Application No. P 35 45 528.4 of the Applicant, a description is given more particularly of bent arms which make it possible to ensure that the outer part of each arm is close to the tire, in an operating position, while allowing the tire to expand when a load is applied. The arms are also slidable with respect to the central housing in order to allow adjustment of the device with respect to the dimensions of the wheel to be equipped and to eliminate the deformation of the tire when the latter comes into contact with the ground.
With regard to the rolling track itself, chains are usually attached to holding elements intended to position the chains with respect to the tire. In these constructions, the holding elements are either directly fixed to intermediate chain segments or have passages for the latter.
It has also been previously proposed to construct the rolling track using shaped elements made from flexible material which are joined to intermediate chain links. Even if the surface of the flexible elements is large with respect to the length of the intermediate chains, the term "snow chains" is still usually applied.
Systems of this type require an adjustment of the length of the antiskid rolling track, which adjustment is carried out by the user acting on the length of a chain segment whose number of links may be altered.
A disadvantage of the known systems is the additional noise caused by the antiskid devices.